This invention relates generally to electronic systems that use redundant components as spares and, in particular, to such systems for use in wafer-scale integrated circuits. Wafer-scale integrated circuits employ large portions of or even an entire semiconductor wafer for the fabrication of a single integrated circuit. Accordingly, there is a greater possibility of production defects in the circuit, and an increased need for providing redundancy in the circuit elements. Redundancy may also be employed to provide for replacement of components damaged after the circuit has been placed in service. Many integrated circuits manufactured today contain spare components for rows and columns of memory cells, or for address decoders and the like.
Typically, the spare components are rendered functional by electrically or optically opening fusible links that are formed as part of the circuit. These fusible links complicate the fabrication process and can result in lower production yields. Moreover, the blowing of the fusible links can cause damage to the circuit and can expose the surface of the circuit to contaminants that degrade the performance of the circuit.
There is a need, therefore, for a technique for connecting redundant components without the use of fusible links or similar devices. The present invention satisfies this need.